Frequently it is necessary because of excessive oil leakage to replace worn crankshaft bearings in internal combustion engines. This usually requires re-boring of the engine block along the axis of the crankshaft so that new oversized sleeve bushings and bearings can be installed in place of the worn bearings.
Heretofore this operation, generally known as line boring, has been difficult, time-consuming and expensive because of the need to carefully center and align the boring tool used for this operation. Some of the difficulties encountered in line boring operations are referred to, for example, in Brooks U.S. Pat. No. 3,751,175, Payne U.S. Pat. No. 4,451,186, and Banoczky U.S. Pat. No. 4,730,958, each of which proposes apparatus designed to ameliorate the problem.